
function addScrollEvent(obj,handle){
	//obj 代表将来调用函数的时候传递过来的标签名，需要把鼠标滚轮事件绑定到此事件上。
	var isFF = navigator.userAgent.indexOf("Firefox");
	if(isFF != -1){
		obj.addEventListener("DOMMouseScroll",scrollFun,false)
	}else{
		obj.onmousewheel = scrollFun;
	}
	function scrollFun(event){
		var down;
		var ev = event ||window.event;
		if(isFF != -1){
			down = ev.detail > 0;
		}else{
			down = ev.wheelDelta < 0;
		}
		handle(down);
	}
}